[vtkusers] How to render the contours of a binary image?

[Thomas Kilgus]

Hi,

I am using a vtkPolyDataMapper to render images as a texture on a plane. 
Some images (in the form of vtkImageData) just consist of the values 1.0 
and 0.0. By means of a vtkLookuptable I can easily render those images 
with a single color (the 1.0 values) and with a transparent background 
(0.0 values). What would be the best way to render just the contours of 
those images?

I already found the vtkContourFilter. But when I use it like this:

       vtkSmartPointer<vtkContourFilter> contourFilter = 
vtkSmartPointer<vtkContourFilter>::New();
       contourFilter->SetInput(image);
       contourFilter->GenerateValues(1, 1.0, 1.0);
       contourFilter->Update();
       texture->SetInputConnection(contourFilter->GetOutputPort());

the whole image is just rendered as a single color.

Is there anything wrong with my code or is the vtkContourFilter just not 
the appropriate filter for my task?

regards
thomas kilgus